Electric steam generator



s. LlvlNGsToNE ELECTRIC STEAM GENERATOR Filed July zo, 1945 J'Trvenor.

Oct. 7, 1947.

Patented Oct. 7, 1947 UNITED STATES; PATENT CFFICE ELECTRICV STEAMGNERAT'ORv Stanley Livingstone, Newton, Mass., assigner to LivingstoneEngineering Company, a corporation of Massachusettsv Application July20, 1945 Serial No. 606,164

13 Claims.

This invention relates to electric steaml generators and has for anobject the provision of a generator which operates to develop steam atcontrolled elevated pressures rapidly, and tov maintain the controlleddeveloped pressure with' The accompanying drawing illustrates a gen-yerator of this invention with a portion thereof shown incross-section.The generator includes a cylindrical casing I provided with upper andlower closure heads I2 and I4, respectively, forming a heating chamberI6 surrounded by suitable insulation I8 and outer casing 20. An inletpipe 22 leads into the bottom of the chamber and is connected through aliquid level gauge 24` to an injector coupling 26 permittingintroduction of liquid, preferably water, into the system to bring theliquid in the heating chamber I6 to about the level shown. By the use ofan injector, water' may be introduced into the systemy while thegenerator is in operation at an internal pressure' above that ofnormal'water main pressure.

A steam outlet 30 leads from the upper portion of chamber I6 throughhead I2 and suitable connections, including a pressure gauge 32 vand asafety valve 34, to a feed pipe 36 leading to a platen, not shown, orother steam consumption device to be supplied with steam. In the case ofa platen, av closed circuit (not shown) is provided back to return pipe38, as conventional in the industry.

The water or other liquid in chamber I6 is heated by an electricalheating unit which', in the form shown in the drawing, comprises threeelectrodes 40 suspended through insulators 42 on an electrode holder 44.Each electrode is sur'- rounded with a cylindrical open ended tubey 46.vSuch a unit is adapted for operation on threephase current supplied froman external source through separate leads 48a, 48h and 48e.

The entire electrode assembly is suspended through the interposition ofrod 50 from a piston 52 operating in a cylinder 62 formed by a pipeconnection 60 leading through heating chamber head I2.

The electrode assembly is thus adapted for vertical movement from aposition as shown, wherein the electrodes are completely immersed in theliquid in chamber I6, to elevated positions wherein the electrodes arepartially or wholly elevated out of the liquid. Such movement is causedby the action of the pressure in chamber I6 upon the under` surface ofpiston 52 which is suitably packed to prevent escape of steam betweenthe piston and walls of pipe 6I).

In order, however, to prevent such movement prematurely, i. e. prior todevelopment in chamber I6 of a desired elevated steam pressure, mygenerator includes structural features which provide opposition to themovement of piston 52 and its suspended electrode holder 44 until afterthe desired pressure for which the generator is set has been developed.For this purpose, cylinder chamber 62 is connected to heating chamber I6through a line 64 joining steam feed pipey 36.

This connection 64 thus acts to maintain the pressure in cylinder 62equal to the pressure in heating chamber I6 during building up of steampressure in chamber I6. Movement of piston 52 and its suspendedelectrode holder 44 is 'thus opposed and prevented.

When a desired elevated steam pressure is developed, for example pounds,there is no longer any necessity for utilizing full power capacity tomaintain the generator (which is capable of f developing much higherpressures) in' operationr at the desired below capacity 69 poundpressure. In order then to cut down the power consumption, I include .inmy generator a suitable control, operating only after the generator hasbuilt up to substantially 'the desired operating pressure, topermitelectrode holder i4 to be elevated relative toV casing IQ to moveelectrodes 40 from the completely immersed position in which they areshown progressively to positions where they are only partially :immersedin the liquid. By thus reducing the electrode surface area in contactwith the liquid, the power consumption is reduced.

This objective is attained by interposing, .in the line 64, a reducingvalve 10. This valve is ade justable and is set to close at a pressureslightly below the desired operating pressure.

The differential in the setting of reducing valve 10 and the desiredoperating pressure will be dependent upon the area of piston 52 exposedto the action of pressure ink heating chamber I6 and the weight of thepiston, rod, and electrode as sembly. In practice, the reducing valve isadjusted to a higher or lower setting to secure the desired pressurereading on gauge 32, although for any singley design, it is possible tocalculate the setting required for any given desired operating pressure.A

Operation is as follows:

A suitable quantity of water havingbeen admitted, and suitableconnection of leads 48 being made to a source of three-phase current,electrodes 4E] will operate to devedop steam in the chamber i6. With thepipe 36 leading through a closed circuit to pipe 38, pressure will buildup in the system including the cylinder 62 and no movement of theelectrodes relative to the liquid level will take place because thepressure above and below piston 52 will remain equal so long as reducingvalve 'I0 remains open. As soon, however, as the pressure has built upto the setting of reducing valve '10, as for instance slightly below 60pounds pressure, the valve 1U closes, and thereafter operates tomaintain the pressure in cylinder 52 at the pressure of the setting ofvalve 1D, regardless of further building up of pressure in chamber I8.Pressure in chamber I6 will then continue to increase over the valve 10setting, until it becomes suiicient, for example 60 pounds, to liftpiston 52 and its suspended electrodes upwardly, overcoming theopposition of the weight of the electrode unit and the lesser pressuremaintained in cylinder G2. As the electrodes 49 rise above the level ofthe liquid in chamber I6, the amount of power consumption progressivelydecreases and the action will be such that the electrodes will continueto rise until such time as the power expended will be insuflicient tomaintain the desired pressure, whereupon, with a drop in pressure, themaintained pressure in chamber 62 will act, with the weight of thepiston and electrode unit, to return the electrodes towards a fullyimmersed full consumption position, and to a position where the immersedsurface area of the electrodes is just sufficient to generate sufficientsteam to maintain the desired pressure. Minimum power will be expendedat such position.

A nice regulation of the steam pressure is thus build-up; reduction incurrent consumption does A not commence until this pressure has beenattained; and thereafter the device automatically adjusts itself tomaintaining the pressure with a minimum of power consumption.

The reference character 8f] indicates a condensate trap which acts toremove condensate from the line 64 to prevent accumulation in chamber62. This device acts to release condensate automatically without drop inpressure in the line E4.

I claim:

1. An electric steam generator comprising a container defining a heatingchamber, an electrode movable in said container from a position adaptedfor complete immersion in a liquid contained in a portion of saidcontainer to positions of only partial immersion therein, meansresponsive to progressively increasing pressure developed in saidheating chamber for moving said electrode from completely immersed topartially immersed position, and control means responsive to saidprogressively increasing heating chamber pressures for opposing andpreventing such electrode movement at any heating chamber pressure belowa predetermined elevated pressure and for permitting such electrodemovement at heating chamber pressures above said predetermined elevatedpressure, whereby as pressure in said heating chamber builds up abovesaid predetermined elevated pressure said electrode is moved to apartially immersed position.

2. An electric steam generator comprising a container dening a heatingchamber, an electrode movable in said container from a position adaptedfor complete immersion in a liquid contained in a portion of saidcontainer to positions of only partial immersion therein, meansresponsive to progressively increasing pressures developed in saidheating chamber for moving said electrode from completely immersed topartially immersed position, and control means responsive to saidprogressively increasing heating chamber pressures for opposing andpreventing such electrode movement at progressively increased pressuresbelow a predetermined elevated pressure and means for terminatingcomplete opposition of said opposing means at heating chamber pressuresexceeding said predetermined elevated pressure whereby as pressuredeveloped in said heating chamber builds up above said predeterminedelevated pressure said electrode is moved to a partially immersedposition.

3. An electric steam generator comprising a container dening a heatingchamber, a cylinder adjacent said heating chamber, a piston in saidcylinder movable towards and away from said heating chamber in responseto pressures developed in said heating chamber and having its 1nner faceexposed to the pressure prevailing in said heating chamber, an electrodeextending into said heating chamber and connected to said piston, andmeans for maintaining the pressure in said cylinder on the outer face ofsaid piston always at least equal to the pressure in said heatingchamber as pressure builds up in said chamber to a predeterminedelevated pressure.

4. An electric steam generator comprising a container dening a heatingchamber, a cylinder adjacent said heating chamber, a piston in saidcylinder movable towards and away from said heating chamber in responseto pressures developed in said heating chamber, an electrode extendinginte said heating chamber and connected to said piston, means formaintaining the pressure in said cylinder always at least equal to thepressure in said heating chamber as pressure builds up in said chamberto a predetermined elevated pressure and means for maintaining thepressure in said cylinder less than the pressure in said heating chamberwhen the latter pressure exceeds said predetermined pressure.

5. An electric steam generator comprising a container dening a heatingchamber, a cylinder adjacent said heating chamber, a piston in saidcylinder having its inner face exposed to the pressure prevailing insaid heating chamber and being movable away from said heating chamber inresponse to pressure developed in said heating chamber, an electrodeextending into said heating chamber and connected to said piston, andmeans for progressively building up pressure in said cylinder on theouter face of said piston to a predetermined maximum elevated pressureas the pressure progressively builds up in said heating chamber, tooppose and prevent movement of said piston until said chamber pressureexceeds said maximum elevated pressure.

6. An electric steam generator comprising a container defining a heatingchamber, a cylinder adjacent said heating chamber, a piston in saidcylinder movable towards and away from said heating chamber in responseto pressures developed in said heating chamber, an electrode extendinginto said heating chamber and connected to said piston, means forbuilding up pressure in said cylinder progressively to a predeterminedmaximum pressure as the pressure pro- Y gressively builds up in saidheating chamber, to oppose and prevent movement of said piston, andmeans for maintaining said pressure in said cylinder less than thepressure in said heating chamber when the latter pressure exceeds saidpredetermined pressure.

7. An electric steam generator comprising a container defining a heatingchamber, a cylinder adjacent said heating chamber, a double actingpiston in said cylinder, said cylinder being connected on each side ofsaid piston for communication with said heating chamber, wherebypressure developed in said chamber builds up equally on both sides ofsaid piston, an electrode extending into said chamber and connected tosaid piston, and control means for cutting oil the communication of saidcylinder on the side of the piston away from said electrode with saidchamber.

8. An electric steam generator comprising a container dening a heatingchamber, a cylinder adiacent said heating chamber, a piston in saidcylinder movable towards and away from said heating chamberprogressively in response to pressures developed in said heatingchamber, an electrode extending into said heating chamber and connectedto said piston, a connection communicating said cylinder on the otherside of said piston from said electrode with said heating chamber and avalve interposed in said communicating connection for cutting oi saidcommunication.

9. An electric steam generator comprising a container deiining a heatingchamber, a cylinder adjacent said heating chamber, a piston in saidcylinder movable towards and away from said heating chamberprogressively in response to pressures developed in said heatingchamber, an electrode extending into said heating chamber and connectedto said piston, a connection communicating said cylinder on the otherside of said piston from said electrode with said heating chamber, and areducing valve interposed in said communicating connection forautomatically cutting off said communication when the pressure in thesteam chamber exceeds a predetermined minimum pressure.

10. An electric steam generator comprising a container defining aheating chamber, a cylinder adjacent said heating chamber, a doubleacting piston in said cylinder, said cylinder being connected on eachside of said piston for communication with said heating chamber, wherebypressure developed in said chamber ybuilds up equally on both sides ofsaid piston, an electrode extending into said chamber and connected tosaid plston, control means for cutting off the communication of saidcylinder on the side of the piston away from said electrode with saidchamber, and a condensate trap for releasing accumulation of condensatein said cylinder.

11. An electric steam generator comprising a container defining aheating chamber adapted to contain liquid to be vaporized, an electrodemounted for movement in said container between positions of greater andless immersion in said liquid, means for moving said electrode, andcontrol means responsive to the pressure within said container forinitiating said movement only when said pressure exceeds a predeterminedelevated pressure.

12. An electric steam generator comprising a container defining aheating chamber adapted to contain liquid to be vaporized, an electrodemounted within said chamber for movement between positions of greaterand less immersion in said liquid, means responsive to the pressurewithin said container for moving said electrode to a position of lessimmersion, and means responsve to the pressure within the container forpreventing operation of said iirst means when the pressure within thecontainer is less than a predetermined elevated pressure.

13. An electric steam generator comprising a container forming a heatingchamber adapted to contain liquid to be vaporized, an electrode withinsaid container, a piston connected to said electrode and movable to movesaid electrode between positions oi greater and less immersion in saidliquid, a cylinder for said piston having one of its head spaces incommunication with the interior of said container, whereby increase ofpressure within the container tends to move said electrode into aposition of lesser immersion in said liquid, a conduit connecting theother head space of the cylinder with the interior of said container,and means for reducing the pressure transmitted to the piston throughsaid conduit when the pressure within said container exceeds apredetermined value.

STANLEY LIVINGSTONE.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,714,578 Weiss May 28, 19291,706,146 Davidsen Mar. 19, 1929 FOREIGN PATENTS Number Country Date319,521 Germany Mar. 6, 1920

